Not applicable.
Not applicable.
The present invention relates to apparatus for mixing gases and liquids in general and to apparatus for aerating contaminated liquids to promote oxidization and purification in particular.
Standards for the purity of water in rivers, lakes and groundwater are continually increasing in response to legislation, regulation, and community demand. These increasingly stringent standards place a burden on the producers of wastewater, for example, users of pools and spas, agribusiness operators, paper and pulp producers, and others, to discharge wastewater which does not introduce prohibited levels of contaminants or chemicals into the surroundings and groundwater.
Due to the strict regulations, maintenance of water purity by the use of chemical additives such as chlorine in pools and spas has become less desirable.
It is common under many state and federal regulatory regimes that any unauthorized discharge of organic or inorganic waste, or bacteriologically contaminated materials, which exceed regulatory levels must be immediately reported to the authorities.
Although transportation of contaminated wastewater to off-site authorized disposal facilities is permitted, such transportation is in most circumstances prohibitively expensive, especially where large volumes of wastewater are involved. If the contaminated wastewater is categorized as hazardous, prior authorization and permitting may be required.
Wastewater contains biochemical oxygen demand (BOD), ammonia nitrates, phosphorous, bacteria and virus. Prior art systems have introduced chemical agents, particularly chlorine, ozone, or a combination thereof, to oxidize and purify the wastewater. Inorganic contaminants are oxidized to less soluble oxides and organic components are converted to carbonaceous residuals and carbon dioxide. Conventional aerators and injectors utilize pressure and velocity changes of the wastewater flow to introduce air, oxygen or ozone as a vast quantity of minute bubbles ranging in size from about 40 microns to 0.5 microns in diameter. However, prior art injectors typically require high pressures or high flow rates to achieve effective aeration.
In my U.S. Pat. No. 5,298,198, the disclosure of which is incorporated by reference herein, I disclosed an aerator which included an inlet nozzle in a wastewater stream with a flared inlet bore, and a downstream outlet nozzle, positioned after an air inlet, which has a flared bore of greater diameter. This aerator produced excellent results, and was successful at introducing significant quantities of air bubbles of very small size at economical pumping levels. However, even greater performance levels would be desirable. Aerators of greater efficiency would make it possible to retrofit existing installations for greatly increased capacity without significantly increasing the size of the equipment. Moreover, because aerators are usually a part of a continuous treatment process, any improvement in efficiency, that is in converting pump energy into mass of oxygen introduced into the treated water, will be multiplied over many hours of operation and can represent considerable cost savings in terms of reduced power charges, and reduced pump requirements.
The aerator of this invention has a housing which contains a fluid inlet nozzle and a fluid discharge nozzle positioned on either side of an air inlet formed in a T-pipe. The fluid inlet nozzle has a bore with a flared inlet followed by a cylindrical outlet. The cylindrical outlet has a spiral groove or rifling which extends to the end of the inlet nozzle, allowing the infed contaminated water to pass through and be swirled by the spiral groove, and then exit into an expansion chamber in communication with the air inlet, where air is entrained within the swirling water. The depth of the spiral groove may be from 0.001 inches to 0.125 inches, and may have from 1 to 32 turns per inch. Banks of the aerators are used in a wastewater treatment system, having a rectangular tank with a serpentine flow path. Dissolved oxygen meters provide data to a Programmable Logic Controller to control the pumps recirculating liquid within the tank. Pumps are turned on and off to achieve target minimum levels of dissolved oxygen.
It is an object of the present invention to provide an aerator which efficiently introduces oxygen into water to be treated.
It is another object of the present invention to provide an efficient aerator which can be manufactured economically.
It is a further object of the present invention to provide a water treatment system with increased dissolved oxygen injection based on feedback.
Further objects, features and advantages of the invention will be apparent from the following detailed description when taken in conjunction with the accompanying drawings.